1. Field of the Invention
This invention relates to a method for treating ischemnic brain stroke and/or a method for hypothermic treatment of the brain.
2. Discussion of the Prior Art
Medical investigators have, for decades, unsuccessfully sought an effective early treatment for ischemic brain stroke. The more quickly the ischemic brain tissue receives arterial blood the greater the chance that permanent injury can be reduced or prevented. With the exception of the recently announced improved outcomes for patients treated with intravenous tPA, there has been no effective treatment for acute ischemic stroke. In U.S. Pat. No. 5,011,468 there is disclosed a coronary sinus retroperfusion and retroinfusion apparatus, system and method that may be used in cerebral retroperfusion The method discloses occluding both jugular veins by balloon catheters or, alternatively, occluding the drainage paths from higher up in the brain if desired, and continuously pumping arterial blood into one or both of the cerebral sinuses. The time of balloon inflation is disclosed as being adjustable so that a desired cerebral sinus pressure can be achieved with a selected blood flow rate. Notwithstanding the teaching of a method for coronary sinus infusion, there has been great difficulty in the past in achieving good, reproducible results with cerebral retroperfusion in animals and there are no prior human investigations. There is therefore a need for an improved method which can be safely utilized for instituting clinically effective cerebral retroperfusion as well as retroinfusion for treating ischemic brain stroke.
A further aspect of the invention can be combined with the foregoing treatment of ischemic brain stroke or alternatively used independently for the hypothermic treatment of the brain. Cooling the brain is a well-recognized and scientifically proven method of preserving brain tissue in the presence of ischemic stroke or brain trauma. It is well known, for example, that lowering the temperature of brain tissue lowers brain tissue metabolism, inhibits the release of harmful neurotransmitters and prevents changes in the blood brain barrier that can lead to cell death. In spite of this knowledge, and the benefits of this treatment, applications of various cooling methods have been generally unsuccessful.
Many of these cooling methods have suffered from a systemic approach where the cooling of the brain is merely adjunct to the general lowering of the whole body temperature. Systemic cooling unfortunately has many undesirable side-effects. For example, cardiac arrhythmia can result when the temperature of the body drops below 28 degrees centigrade. Whole body cooling also can produce a shivering response which necessitates paralyzing and ventilating the patient. Some patients also respond to systemic cooling with coagulopathy problems and an increased risk of infection.
Although methods of selective hypothermic treatment of the brain have been proposed, the apparatus relied upon has generally included external cooling devices which must remove heat through the skull of the patient. Since the skull is relatively thick, it tends to insulate the brain from these external cooling devices. As a result, these external devices are inherently less effective and require more time since the cooling source is relative distant from the core of the brain.
In general, it is an object of the present invention to provide a method for cerebral retroperfusion and retroinfusion which makes it possible to accomplish clinically effective cerebral retroperfusion as well as retroinfusion proficiently and safely for the treatment of ischemic brain stroke. Another object of the invention is to provide a method for cerebral retroperfusion and retroinfusion of the above character in which balloon catheters are placed in the transverse venous sinuses, near the torcular Herophili, to occlude the sinuses while permitting some antegrade flow to prevent excessive pressure buildup in the sinuses.
Another object of the invention is to provide a method for cerebral retroperfusion and retroinfusion of the above character in which the pressure in the transverse venous sinus is measured and the degree of balloon inflation is controlled in accordance with measured pressure
Another object of the invention is to provide a method for cerebral retroperfusion and retroinfusion of the above character in which the flow of arterial blood into the transverse venous sinus is controlled in accordance with the measured pressure.
Another object of the invention is to provide a method for cerebral retroperfusion and retroinfusion of the above character in which the pressure in the transverse venous sinus is measured and thereafter maintained in a range from 10 to 20 mm Hg by controlling the degree of balloon inflation and the flow of arterial blood into the transverse venous sinus in accordance with the measured pressure.
Another object of the invention is to provide a method for cerebral retroperfusion and retroinfusion of the above character in which antegrade blood flow in the transverse venous sinus is at least 10-50% of the normal flow.
Another object of the invention is to provide a cerebral retroperfusion and retroinfusion method of the above character in which the balloons of the balloon catheter are inflated with volumes ranging from 0.1 to 0.4 cc.
Another object of the invention is to provide a method of the above character in which a patient""s arterial blood flow is introduced into the transverse venous sinus at a flow rate between 50 cc/minute and 250 cc/minute.
Another object of the invention is to provide a method for cerebral retroperfusion and retroinfusion of the above character in which the distal extremities of the balloon catheters are located medial to the bilateral superior petrosal sinuses and medial to the bilateral superior anastomotic veins (Labbe""s veins).
Another object of the invention is to provide a method in which a CAT scan is obtained of the patient""s brain prior to introducing the balloon catheters into the vessels and to ensure that there is no evidence of cerebral hemorrhage.
Another object of the invention is to provide a method of the above character in which patients are selected for the method who have Toronto Stroke Scale scores of two or greater and who have experienced a stroke within at least one and less than seven hours.
Another object of the invention is to provide a method of the above character which can be utilized for treating a patient undergoing brain aneurysm clipping and brain tumor resection requiring arterial inflow occlusion.
Another object of the invention is to provide a method of the above character which can be utilized for treating a patient sustaining a non-hemorrhagic angiographic injury in the brain.
Another object of the invention is to provide for hypothermic treatment of the brain with or without the treatment of ischemic brain stroke.
Another object of the invention is to provide for direct retrograde infusion of the brain with cooled autologous blood.
Another object of the invention is to provide for direct retrograde infusion of the brain with cool autologous blood while maintaining the normal body temperature of the remaining body organs.
Another object of the invention is to provide for hypothermic treatment of the brain by introducing cooled blood into the venous system of the brain.
Additional objects and features of the invention will appear from the following description in which the preferred methods are described in conjunction with an apparatus and system of the type shown in the accompanying drawings.